Method of treating milk powder



June 1932' H. SCHIBSTED METHOD OF TREATING MILK POWDER Filed Jan. 29,1925 4 Sheets-Sheet June 1932- H. SCHIBSTED IETHOD OF TREATING MILKPOWDER Filed Jan. 29, 1925 4 Sheets-Sheet 2 June H. SCHIBSTED METHOD OFTREATING MILK POWDER 4 Sheets-Sheet 5 Filed Jan. 29. 1925 June 14, 1932.H scHlBSTED v v I 1,863,355

METHOD OF TREATING MILK POWDER 4 Sheets-Sheet 4 v I E 0 )hr )s'ss B TTOIYEYS gen, showing that.

Patented June 14, 1932 UNITED STATES PATENTlOFFICE HEDGE SOHIBSTE'D, OFSYRACUSE, NEW YOR ASSIGNOB, BY mm; ASSIG .10 mm BORDER COMPANY, 02 NEWYORK, N. Y.. A CORPORATION OF NEW YORK manner or resume mm: rownuaApplication filed January 29,1925. Serial m5. am.

This invention relates toa new and improved method of treating milkpowder, and to the new product, or article of commerce produced thereby.

5 He'retofore, milk powder, particularly milk powder containingbutter-fat, as wholemilk powder, or cream powder, has been of quitelimited keeping quality, and altho packed in air-tight containers, wouldafter a few months, develop a tallowy flavor, due doubtless tooxidization of the butter-fat as a result of the fact that the enclosingreceptacle orcan contains considerable free or uncombined oxygen, notonly oxy en present in the air around the particles of the powder, but

also free or uncombined oxygen contained in or adhered to the particlesof the powder.

By the expression free or uncombined oxygen, as used in thespecification and claims hereof, I mean the element oxygen consisting oftwo atoms of oxygen and being the molecular from '0, contained in air,and I do not mean to include the oxygen chemically combined with theelements in the various constituents of the milk-powder. v

The main object of this invention is the production of a milk powderroduct, or article of commerce, particular y a. ;milkpowder product,which altho containing subso stantial quantities of butter-fat, willkeep for long perlods of time without developing-a tallowy, or rancidflavor.

I have found that the free or uncombined oxygen content of cans adaptedto contain the milk-powder isabout 75 cu. centimeters of ox gen for eachpound of powder. When all ofYtheair in the space around the powder isremoved down toa pressure of one or two millimeters of mercury, therestill remains adhered to or contained in the powder seven or eight cu.centimeters of free or uncombined .oxygen (measured under standardconditions), and this amount of free or uncombined oxygen contained inor adhered to the wder issuflicient in itself to cause development ofthe tallowy flavor referred to.

, Further, ordinary airhas about 21% oxygen, whereas the air containedin or adhered to the powder has ap 'roximatel'y %oxym5} -powder isselective richer in oxygen than ordinary air, and therein its absorptionof the gases of the air, and

its absorption co-elticient is higher for oxygen than nitrogen, so thatthe contained air is fore, more harmful.

For these reasons, it is therefore essential that a portion of thiscontained or adhered oxygen be removed from'the powder. if the desiredkeeping quality is to be attained, and I have found that the free oruncombined oxygen included with each pound of powder should be reducedbelow 5 cu. centimeters per pound if a product having the desiredkeeping qualities is to be'produced.

I have further discovered that the oxygen adhered to or contained in thepowder cannot be removed b merely drawing a vacuum upon the powder, eventho that vacuum be 'asubstantially perfect one, and it is necessary inreducing the free or uncombined 0 gen content below the limit statedthat the milk powder .be maintained under a vacuum or surrounded by agas that is a vacuum for free or uncombined oxygen for a considerableperiod of time, for illustration,20 hours, during' which time theadhered or contained free or uncombined oxygen is slowly given up by thepowder, and t e retained free or uncombined oxygen is thereby reduced inamount below the limit stated.

Further, I have discovered that most advantageous results are obtained.when the method is carried on with milk powder packaged in air-tightcontainers whichv have a vent-hole of extremely small area, not greaterthan .0002, and preferably approaching .00006 sq. inches for each poundof powder the container is adapted to hold, whereby the container may besealed at atmospheric ressure, while the cans are still giving 0 gasthrough the vent-hole to prevent ingress of air to the container.

I have discovered a recess bymeans of which the free .or uncom inedoxygen in each one pound of powder may be reduced below five cubiccentimeters (measured under standcard conditions) and preferably down toabout i 3.5 cubic centimeters per pound of powder,

whereby development of the tall flavor 7 [is eliminated, and further,w gni.

site air-tightness of the receptacle may easily be determined by reasonof a vacuum developed in the containers through absorption of gases bythe powder enclosed in an airtight container, and I have produced such aproduct, and have already kept such product without the development of atallowy flavor for more than one and one-half years.

Other objects and advantages relate to the details of the process andthe detailed characteristics of the product, all as will more fullyappear from the following description, taken in connection with theaccompanying drawings. The apparatus illustrated in the drawings is thejoint invention of Irving S. Merrell and myself, and is designed toconstitute the subject matter of-a co-pending application.

In the drawings v Figure 1 is a top plan view of such apparatus.

Figure 2 is an elevation partially in section of a unit of theapparatus- Figure 3 is a top plan view of one of the kettles or tanks.

Figure 4 is a section on line 44, Figure 3.

Figure 5 is a top plan view partially in section of the distributinghead.

Figure 6 is a section on line 66, Figure 5.

Figure 7 is an elevation of the article of commerce produced by thisprocess previous to the sealing of the vent.

The process will be here described in connection with the apparatusillustrated, which as here shown, consists of a plurality of, in thisinstance seven kettles or tanks numbered -1 on the drawings, arrangedsubstantially concentrically about a distributing head 2-, altho sucharrangement is not essential to the apparatus. Each tank or kettle, ashere illustrated, comprises a vertically arranged cylindrical body part3 of any suitablediameter and depth, combined with a cplver. 4 adaptedto close the kettle airtig t.

For this purpose, the tank near its upper end is provided with anexternal annular channel or groove -5 formed by welding or otherwisesecuringan angle-bar .6-- to the outer surface of the tank near itsupper end. This annular chamber is adapted to be filled, orsubstantially filled with a suitable sealing composition, as forinstance, a paraffin beeswax mixture which melts easily under the actionof heat, and solidifies rapidly under the action of cold. Forco-operation with the annular composition-containing channel, the cover.4 is formed with a circumferential depending flange 7' terminating in apipe secured to the lower end of the flange in any suitable way, as bywelding, such: pipe having an inlet 8 and an outlet=+9+ for either steamor cold water, the inlett-w.+-:8 being suitably connected to a source ofsteam, and also a source of water,

suitable valves being provided for controlling flow of both fluids.

The flange 7 depends within the channel.-5 and the sealing compositionhardens about the pipe 10 in the channel 5 to thereby form an absolutelyair-tight joint, and for the purpose of hastening the hardening of thecomposition, cold water may be forced through inlet 8 into the pipe-10-.

In addition, the cover -4 is held in proper position by means of aseries of pivoted clamps, each consisting of a threaded rod 1l-- pivotedon a bracket 12 and cooperating threaded nut 13- for engaging the uppersurface of bifurcated lugs 14 secured to and projecting outwardly fromthe edge of the cover 4 so that the threaded rods 11 may move into thebifurcated portions of the lugs, and the nuts 13 may then be tightenedto lock the cover rigidly in place.

18 in the form of a pipe, and each of these pipes extends to, opensupwardly through and is secured to the distributing head 2.

This distributing head, as illustrated, is formed of a substantiallyflat plate, and has a circular flange 19- rising from its surface nearone edge, and a plurality of circular flanges 20 arising from itssurface and concentrically arranged about the flange -19, so as to forma series of cup-shape recesses, in this instance seven in number, onefor each kettle or tank 1 and concentrically arranged about the chamberformed by the flange 19-. Each of the chambers formed by the circularflanges 20 has a central opening or perforation in its bottom wall,through which a pipe 18- extends,

leading from a tank or kettle 1-, and this pipe is preferably asillustrated, threaded into a cylindrical sleeve 21, which has a portionof the interior of its upper wall preferably plain for slidingengagement with the pipe projects upwardly; Additional securing meansmay be provided in the form of a ring or washer 23 surrounding the pipe18- below the distributing head -2 and engaged by the bolts 24 whichsecure the sleeve 2l in place. V 4 It will be seen, therefore,'that eachof th tanks 1--- has a pipe -18 and that the tank extends upwardlythrough an opening in the bottom wall of a respective'chamber formed byone of the upstanding circular flanges -20--.

In much the same manner, the chamber formed by the upstanding circularflange -19 is provided with a concentrically arranged sleeve -25 withinthe chamber, and aligned withan opening in thefbottom wall of thechamber throughwhich a pipe 26- projects for threaded engagement withthe interiorly' threaded portion .of thewsleeve 25. The sleeve -r25preferably'has its base flanged outwardly and secured to the bottom wallof the chamber within the flange -19 in any suitable way, as by bolts27- which bolts also clamp the ring orwasher 28 surrounding pipe 26against the lower surface of the distributin head -2''-.

The sleeve -25 is prefera ly of somewhat greater axial length than thesleeves 21 and the interior surface'of its upper portion is preferablysmooth ,for sliding engagement with the other end of the U-shape pipe oroke 22.

It wil be obvious, particularly from the disclosure of Fig. 6 that thesleeves -21- are concentrically arranged about the sleeve -25- and areall spaced ual distances from the sleeve 25-: so that t e end -27- ofthe U-shape pipe 22- can be slidably positioned in the upper portion ofany one of the sleeves -21, whilethe opposite end 45 28 of the U-shapepipe -22-- remains in 'slidable engagement within the sleeve 25, wherebythe pipe --26 leading from the high: vacuum pump 29 may be brought intocommunication with any one of the pipes 18 and thereby intocommunication with the interior-of any one of the tanks or kettles 1--.

It is essential in the operation of this 'ap-- paratus for carrying outthe method of this invention, that these connections beabsolutelyair-tight in order that the pressure in any one of the tanksmay bereduced as low as one or two millimeters of mercury, and for result eachof the annular chambers formed by the "upstanding flanges -20 and theconcentrically at d sleeve 21 and the chamber form by the flange 19- bythe application of cold, as for instance, a

of pipe 22- is formed with a laterally exand concentrically arrangedsleeve -25 is filled, or partially filled with a composition thatpreferably can be rapidl melted by the application of heat and rapidlyhardenedmixture of paraflin and beeswax.

At the end -28 the U-shaped connecting pipe 22- is provided with alaterally extending flange 30- formed at its edge 7 with a dependingflange -31-, as perhaps best-illustrated in Figure 6. In other words,this structure is insubstantially the form of an angle-iron surroundingthe end 28- of pipe 22 g and the depending flange 31 terminates in apipe -32- extending around the lower end of the flange, and welded orotherwise secured thereto, for con- 'veying either steam to melt thesealing compound, or cold water to hasten the hardening of the compound.

As illustrated, the flange '-30 comes into contactwith the upper edge ofthe sleeve --25 when the end 28 of the pipe is positioned within thesleeve -25-, as illustrated, and the flange -31- and pipe -32-- extendinto the sealing compound, whereby the joint between pipe -28- and pipe-26- is rendered absolutely air-tight In like manner, the opposite end-27 tending circular flan e 33- formed at its edgewith a circularepending flange -34 provided at itslower end with a pipe 35-.- forconveying either steam or water like manner as the pipe 32-, and thisstructure may be secured to the end 27 of pipe -22- in any suitablemanner, as by weldin 7 etc. and in connecting the pipe 22 wit any oneofthe pipes ,18-, as may be desired; the circular pipe 25- is immersed orpartially immersed in the sealing composition within the chamber formedby the upstanding flangee-20, so that an absolutely tight joint may bemade between the end -27-- of pipe -22- and any one of the pi s '-18. V

or the purpose of assing steam through the pipe 32- and t e pipe 35--, aconnecting pipe or conduit 36 is shown leading to any source of steam,and also any source of water, suitable valves being utilized forcontrolling theflow of both the steam and the cold water, and conduit76- is shown as connected to pipe 35', the fluid passing around the pi-35- and escaping through connecting pipe --36 to the pipe 321'rsperhaps best illustrated in Figure 5. The fluid then passes around thepipe 32-' and escapes through U-shaped tube --37-- to one of the pipes-38-leading toa header 39 connected by pipe -40-- to anysuitable waste.For the purpose of connecting the U-shape discharge pipe 37 with theheader'- 39- ;in all positions of the pipe -22- the distributing head 2is formed with a series of perforated bosses 41 concentrically arrangedabout the sleeve 25 and of a number equal to the number of tanks 1, andthe number of chambers formed by upstanding flanges -20-', and soarranged that when the end 27 of pipe 22' is arranged for communicationwith any one of the pipes -18, the free end of the pipe 37 will beslidably posi tioned within one of the respective bosses 4l.

Each of these bosses, as here shown seven in number, is connected by athreaded union with a. pipe 38 leading to the header 39 which'is in theform of an elongated cylinder extending substantially the entire widthof and arranged beneath the distributing head *2. However, this methodof discharge is not. essential, as each of the pipes 37 may discharge inany suitable way directly into a waste, if. desired. I

As here shown, the pipe 22 is carried by a rotary and axially movablestud 4=2 journaled, as illustrated, in a two part bracket 43 carriedfrom the distributing head 2. The lower end of this stud may, as shown,be threaded into one section of a two part clamp 4t., the two parts ofthe clamp being secured together about the pipe 22. in any suitable andwell .known manner, as by the bolts illustrated, and by thisconstruction, the clamp 44 is tightly secured to the pipe 22 nut 45being provided for locking the clamp to the stud 42 the nut as shown,being spaced some distance from the lower surface of the adjacentportion 0 bracket 43 so as to permit axial, as we I as rotary movementof stud -42.

The axial movement is suflicient in length to permit removal of the end27 of pipe 22- from sleeve 2l, and the pipe 22 may then be moved aboutthe end -28- as a pivot for insertion into any other one of the sleeves21, the sleeve 25- being of sufiicient axial length so as to preventdisengagement of the end 28 of pipe 22 from the sleeve within the normallimits of movement of clamp -44.

However, the clamp, stud and brackets may be omitted, if desired, as theU-tube will support itself in any of the desired positions.

It will be obvious that by this construction, the vacuum pump 29 may bebrought into absolutely air-tight communication with any one of thekettles 1 for producing in that kettle a substantially perfect vacuum.

' The kettles -l are further provided with an inlet pipe 46 for a gas,such as carbondioxide, nitrogen, or any other suitable gas notcontaining free or uncombined oxygen. The process will be here describedin connection with CO with the understanding that gases as abovedescribed, may be used in its place with like results, except whereadditional advantage may be specifically stated.

which leads through a hot-water tank 51' to any suitable and ordinarycontainers -52 for carbon-dioxide, reducing valve -53- being providedforvcontrolling the flow of the gas, and preferably as shown, the pipe49 is coiled within the hot-water tank 51 to effect any desired heatingof the gas.

Each tank 1 is provided with a suitable independent relief device so asto limit the pressure that can be producedwithin the tank so that itcannot rise above a pre-determined amount, as for instance, 12 pounds,and yet this relief device is of such character as to permit theproduction of a perfect, vacuum within the tanks.

This structure consists of a pipe -54 connected to the tank, and leadingto a U- tube, one leg 55- of which is of somewhat .inlet of air theretothrough the U-tube when suction is produced ,Witlr'n the tanks.

Upon theproduction of pressure in any one of thetanks 1' should thatpressure goabove the pre-determined amount, as for instance, 12 pounds,the l'nercury contained in its respective U-tube will be blown bythepressure into the receptacle 57 thereby permitting the escape of the gaswith which the tank is charged to relieve the pressure. By opening valve58 the mercury is permitted to ret-urnto the U-tube for future automaticcontrol.

Each pipe -l8 contains a valve 59, by means of which communication withits respective tank is controlled, and for the purpose of rendering thisvalve structure airtight, it is enclosed within a box or receptacle60-containing oil or other liquid, to thereby produce an oil-sealrendering the valve air-tight under all conditions of opera tion.

.For the purpose of assisting in opening the cover --4 of any one of thetanks 1, and maintaining it in open position, each cover is shown asprovided with a pair of weights 61- lying outside the pivot rod. -l 6.,and pivotally mounted on'extensions from package is first placed in asuitable can or the cover 4-, so as to substantially balance the cover.

The method of this invention as carried out in connection with theapparatus as shown, may be described substantially'as follows Themilkpowder which it is desired to container A-. Usually these cans come withseparate covers, and the covers are provided with a vent-hole -b havinga crosssectional area of from .00006 to .0002 sq.- inch per pound ofpowder the, can is adapted to contain, i. e., we are assuming that thecans are substantially filled with powder.

The cans are sealed with these. covers, and are then placed in baskets62 as best illustrated in Figure 4. These baskets may contain anysuitable number of cans, dependent upon their size,and the amount ofpowder which each can is adapted to contain. As at present used, eachbasket is adapted to contain approximately 400 one-pound cans.

Each basket 62- is provided with a loose cover -63- that is rested uponthe upper" edgeof the basket, as illustrated in Fig. 4, and does notform an air-tight joint with the body of the basket. Any number of these"baskets may be placed in one ofthe tanks -1, and as at present used,the size of the tanks --1-- is sufiicient to. accommodate three basketsstacked one upon the other, and each is equipped with a loose cover'63-.-

The tank 1- is then sealed absolutely air-tight by means of the cover-4- having its edge set in a suitable compound or mixture, as abovedescribed, which solidifies'to "seal the joint.

The tank is then connected tothe vacuum pump -29 by vmeans'of theU-shape pipe '22- bringing its respective pipe 18 into communicationwith pipe 26-, the

joints between these pipes being sealed by solidification of the sealingcompound about the depending flanges on pipe -22.

The vacuum pump -29 is then started and the valve ----59 to the tank isgradually opened, drawing vacuum at-a speed of apper minute. en thevacuum has reache about 27 the valve 59- isopened wide. At the end of15"minutes the remaining pressure in the.

tank -1- is about one millimeter of mercu the'valve. 59 is then closed,and the tan withthe enclosed baskets and cans is allowed to stand 20hours, during which time the powder gives off aportion of its containedor absorbed oxygen, or perhaps preferably in i order to eliminate theentry of air oroxygen to, the kettle as induced by the high vacuumtherein, the respective valve -5-- is opened,

the reducin valve -5? bein 'roperly re ulated, and the tank 1- v hibhhas bee n evacuated, is charged with carbon-dioxide, preferably up toapressure of about two pounds per square inch. This charging as atpresent carried on, requires about six minutes.

The valve is then closed and the tank with its enclosed baskets allowedto stand twenty hours, during which time the pressure of carbon-dioxideisused, will gradually decrease from twopounds to the square inch downto about pound per square inch, the final pressure varying somewhat withtemperature and barometric pressure.

When a gas such as nitrogen-is ultimately used for charging the powder,it is perhaps preferable to hold the tank 20 hours under high vacuum,but in the case ofCO which is considerably absorbed by the powder, it ispreferable to charge the tank before holding it, as this will reduce tosome extent the ultimate vacuum developed in the cans after sealing, aslater described.

At the end of the 20 hour period of treatment under either condition,the tank -'-1-' is again connected to the vacuum pump 29- by a propershifting of pipe-22- under control of valve --59- and the tank is againevacuated, and the pressure will again be reducedto about 1 millimeterof mercury, and the free or uncombined oxygen content is reduced by thisoperation to approximately 3.5 cubic centimeters for each :pound ofpowder, which condition is below the limit required for producing thedesired keeping quality of the powder, and eliminating the developmentof a tallowy flavor.

The communication with thevacuum pump is then cut oil, the respectivevalve -50' opened and under control of regulatingvalve 53, the tank ischarged with carbon-di oxide to a pressure of about 10 pounds per squareinch. This charging super-saturates the surface of the particles of thepowder with carbon-dioxide, therebycausing a slow streamofcarbon-dioxide to escape through the minute vents in the cans forabout the half hour after the pressure has been released, thereby,during the period necessary to the sealing of the vent-holes, preventingthe ingress of air through the vent-holes to the interior of the cans.

The tank charged with carbon-dioxide to a pressure of substantially 10pounds per square inch is allowed to stand about 30 minutes, and thepressure is then gradually relieved discharging the gas into theatmosphere. This operation requires about two or three minutes in orderto get down to atmospheric, pressure. When atmospher c pressure isreached in the tank 1, the cover 4 is lifted, after steam has beenpassed through pipe -10 to melt the wax,

Calls are preferably within thirty minutes from the time the pressurewas released, and as the 'ving ofi carbon-dioxide during that perioentry of oxygen is not permitted.

The article of commerce so produced consists of an air-tight containercharged with a gas not containing free or uncombined oxygen andenclosing milk-powder in which the free or uncombined oxygen content isbelow five cubic centimeters (measured under standard conditions) foreach contained pound of milk powder, whereby a milk powder product,particularly one containing butter-fat is produced having a keepingquality never before attained or even approached. The cans may be testedfor air-tightness in any suitable l Vhen carbon-dioxide is the gas used,the cans are placed with the bottom up and left standing for at leastseven days, during which time it is found that the carbon-dioxide willbe gradually absorbed and a vacuum of from five to eight inches ofmercury will be produced within the cans as a result of this partialabsorption of the carbon-dioxide by the powder, and the vacuum existingin the cans will pull in the ends of the can.

-After one weeks time, the cans are all tested for depression ofthe'bottom ends in any suitable manner, as by means pf an electricbell-tester, which causes a bell to ring if the bottom end depressiondoes not exceed a certain set distance The absorption of carbondioxideby the powder and the vacuum resulting within the cans therefromprovides a certain and sure way of detecting at any time whether any ofthe cans are leaking as the vacuum increases fora considerable period oftime up to 11 to 15 inches of mercury, and the leaking cans can besorted out as it is essential to the keeping quality of this article ofmanufacture that the cans be air-tight. This product, in addition to thefeatures above described, has the further characteristic that a vacuumexists in the container.

In the use of the apparatus here shown, the tanks may be all in thecourse of utilization at the same time, i. e. tank 1- may be filled anda vacuum drawn upon it. In the meantime, tank 2 is being filled, andwhen the proper degree of vacuum has been reached in tank No. 1, thepipe -18 leading from tank 2- is brought into communication with thepump by the movable pipe 22 and while tank 1 is being charged withcarbon-dioxide, or other gas, a vacuum is being drawn upon tank 2. Inlike .manner when the proper vacuum has been obtained in tank -2-, pipe22 is lifted up and moved around so as to bring tank 3 intocommunication with the vacuum pump. So that the apparatus here shownconstitutes a means whereby a substantially continuous process may becarried on throughout the 55 day, the tanks being allowed to stand for20 hours, and they are then successively evacplated, charged withcarbon-dioxide, emptie and the can sealed.

After the cans containing CO or gas absorbed to a similar extent havebeen allowed to stand for about seven days, during which time a partialvacuum is produced Within the cans, it is easy to determine the leakingcans by the fact that the ends of the can are drawn in, and after thathas been determined and the good cans selected out, additionalcarbondioxide or suitable gas may be injected into the cans in anysuitable manner so as to relieve the vacuum tending to collapse thecans, should that be desirable, and the cans may then again be sealed.

It will be obvious, however, that the process of this invention does notdepend for its operation upon the articular apparatus shown, as otherand di erent apparatus may be used and adapted for the purpose, andvarious changes may be made in the details of the process and in theparticular pressures utilized and the particular gas, all withoutdeparting from this invention as set forth in the appended claims.

I claim: 1

1. The process of packing milk-powder comprising enclosing themilk-powder in a container air-tight except for a minute opening,enclosing a plurality of containers in an air-tight kettle, drawing asubstantially perfeet vacuum within the kettle, then admitting a gas notcontaining free or uncombined oxygen under pressure to the kettle, thenallowing the kettle to stand with its enclosed.

containers for a considerable period of time while the entrance ofoxygen is prevented, again drawing a substantially perfect vacuum withinthe kettle to thereby reduce the free or uncombined oxygen of the powderin the containers'to an amount not substantially greater'than five cubiccentimeters for each pound of powder, again charging the kettle with agas that does not contain free or uncombined oxygen so as to produce apressure sufliciently above atmospheric pressure I so that the egress ofgas from the containers through said openings will prevent the ingressof air during the time necessary to effect sealing of said openings, andthen sealing the openings in the containers.

2. The process of packing milk-powder comprising enclosing milk-powderin a container air-tight except for a minute opening, enclosing aconsiderable number of such containers in an airtight kettle, thenproducing a substantially perfect vacuum within the kettle, thenadmitting a gas that does not contain free or uncombined oxygen to thekettle so as to produce a pressure within the kettle not substantiallyless than two pounds per square inch, then holding the kettle as chargedfor a period approximating twenty hours, again producing a substantiallyper- I fectvacuum within the kettleto reduce the free orruncombinedoxygen content of the powder in the containers to an amount notsubstantially greater than five cubic centi meters 'for each pound ofpowder, then charging the kettle with a gas which does not contain freeor uncombined oxygen up to a pressure approximating ten pounds persquare inch, then removing the containers from the kettle and sealingthe openings in the cone tainers without permitting increase ofuncombined oxygen content substantially above five cubic centimeters perpound of powder. In-witness whereof I have hereunto set my hand this dayof January, 1925.

. SCHIBSTED.

